The reciprocal relationship between heme oxygenase and nitric oxide synthase in the organs of lipopolysaccharide-treated rodents.

The production of nitric oxide (NO) by inducible NO synthase (NOS) and carbon monoxide (CO) by inducible heme oxygenase (HO) contributes greatly to endotoxemia. Reciprocal relationships have been proposed between the NO/NOS and CO/HO systems. However, the interaction between these systems during endotoxemia is unclear, and it is unknown whether the interactive behavior differs among organs. Using endotoxic rats, we studied the effects of the inducible NOS (iNOS) inhibitor L-canavanine (CAN), and the HO inhibitor zinc protoporphyrin (ZPP) on gene expression and protein levels of iNOS, endothelial NOS (eNOS), inducible HO (HO-1), and constitutive HO (HO-2) in the brain, lung, heart, liver and kidney tissue. Intravenous injection of LPS significantly increased iNOS and HO-1 gene expression in all organs. The effects of LPS on eNOS gene expression differed among organs, with increased expression in the liver and kidney, and no change in the lung, brain and heart. ZPP administration down-regulated the LPS-induced increase in HO-1 expression and produced a further increase in iNOS expression in all organs. These data suggest that the CO/HO system modifies the NO/NOS system in endotoxic organs, and that there were only minor organ-specific behaviors in terms of the relationship between these systems in the organs examined.

The influences of propofol and dexmedetomidine on circadian gene expression in rat brain.

INTRODUCTION: There are circadian genes whose expressions were affected by sevoflurane. We hypothesized that propofol and dexmedetomidine also have influences on the expressions of circadian genes. MATERIALS AND METHODS: Seven-week-old rats were cannulated and propofol (600 microg/kg/min, 1 ml/h, n=6: group P6H), dexmedetomidine (1 microg/kg/min, 1 ml/h, n=6: group D6H), 10% lipid (1 ml/h, n=6: group L) and normal saline (1 ml/h, n=6: group N) were infused intravenously for 6h; rats were decapitated soon or 24h after awakening from anesthesia (groups P24H n=6 and D24H n=6). Real time reverse transcription-polymerase chain reaction was performed using rat whole brain and the expressions of circadian genes were measured. RESULTS: In the P6H group and the P24H group, the whole expressions of seven genes were changed significantly compared with the L group. In the D6H group, the whole expression of seven genes was changed significantly compared with the N group. In the P6H group, all gene expressions except for Tef (thyrotroph embryonic factor) were changed significantly compared with the L group. In this group, the expression of Dbp (D site albumin promoter binding protein) was increased, and the others were decreased. In the D6H group, all gene expressions except for Dbp and Tef were decreased significantly compared with the N group. For the two anesthetics, the expression patterns were different only in Dbp. CONCLUSION: We showed that propofol and dexmedetomidine have influences on the circadian gene expressions.

Expressions of genes encoding drug-metabolizing enzymes are altered after sevoflurane, isoflurane, propofol or dexmedetomidine anesthesia.

We previously showed that sevoflurane anesthesia affected the expression ratios of 177 of 10,000 genes in multiple organs of rats by microarray analyses. The maximum number of altered genes was detected in the liver, and included several genes characterized as encoding drug-metabolizing enzymes (DMEs). Here, we investigated whether alterations of pharmacokinetic gene expressions after anesthesia differed between inhalation and intravenous anesthesia, and how long the alterations persisted after awakening from anesthesia. Livers were obtained from rats (n = 6 per group) anesthetized with sevoflurane, isoflurane, propofol or dexmedetomidine for 0 or 6 h, and rats awakened for 24 h after anesthesia for 6 h. The mRNA expression ratios of eight genes encoding DMEs that showed the greatest alterations in the previous study, namely Cyp7a1, Cyp2b15, Por, Nr1i2, Ces2, Ugt1a7, Abcb1a and Abcc2, were measured by quantitative real-time reverse transcriptase-polymerase chain reaction. The expression ratios were mostly increased after 6 h of anesthesia and returned to their control levels at 24 h after awakening from anesthesia. However, the expression ratios of some genes remained elevated for 24 h after awakening from anesthesia. There were differences between inhalation and intravenous anesthesia, and interestingly, between sevoflurane and isoflurane and between propofol and dexmedetomidine.

The effects of dexmedetomidine on human neutrophil apoptosis.

The purpose of the present study was to evaluate the effect of dexmedetomidine, used as a sedative in the intensive care unit, on human neutrophil apoptosis and superoxide production in vitro. Neutrophils from healthy volunteers were incubated in different concentrations of dexmedetomidine (1, 10 and 100 ng/mL). Apoptosis was assessed by Hoechst 33342 staining, caspase activities and loss of mitochondrial transmembrane potential (MTP). Superoxide production was determined by the WST-1 assay. After 24 h of incubation, dexmedetomidine accelerated neutrophil apoptosis in a dose-dependent manner and 100 microM yohimbine did not inhibit the apoptosis. Treatment with 100 ng/mL of dexmedetomidine significantly enhanced the activation of caspases-3/7, -8 and -9, and also markedly increased the number of neutrophils with decreased MTP. At 24 h, the suppression of superoxide production was dependent on dexmedetomidine concentrations. However, a clinically relevant concentration (1 ng/mL) of dexmedetomidine did not affect neutrophil apoptosis and superoxide production. These results suggest that high doses of dexmedetomidine induce apoptosis without alpha(2)-adrenoceptors stimulus and inhibit superoxide production after long-term incubation. The mechanisms of dexmedetomidine-induced apoptosis are associated with the caspase cascade and loss of MTP.

Circadian gene expression is suppressed during sevoflurane anesthesia and the suppression persists after awakening.

General anesthesia is routinely used as a surgical procedure and its safety has been endorsed by clinical outcomes; however, its effects at the molecular level have not been elucidated. We previously showed that inhalation anesthesia affects the expression of 1.5% of 10,000 genes, which included so-called circadian genes. In the current study, we confirmed that inhalation of sevoflurane alters circadian gene expression, and investigated whether this alteration persists after awakening from anesthesia. Rats were anesthetized with 4.0% sevoflurane for 0 h, 2 h and 6 h (n=9 each group), before being sacrificed. Rats were also anesthetized for 6 h and allowed to recover after anesthesia, then sacrificed 2 h, 6 h and 24 h after awakening (n=9 each group). Anesthesia was started for each group so that all rats would be sacrificed at 13:00, and gene expression in the whole brain was examined using real-time RT-PCR. Expression of the genes encoding Per2, Dbp, Arc, Egr1, Krox20 and NGFI-B was suppressed during inhalation of sevoflurane for 2 h and 6 h. Although the suppression tended to be alleviated after awakening from anesthesia, the expression levels after a recovery period of 24 h remained significantly lower than the control levels of these genes, except for Krox20. We demonstrated that circadian gene expression is suppressed in whole brain during sevoflurane anesthesia, and the suppression continues for at least 24 h after termination of sevoflurane treatment. This suggests that sevoflurane anesthesia may have effects at the molecular level and that these effects are long lasting.